1. Technical Field
The present invention relates to an ink set for ink jet recording, a recording apparatus, and a recorded matter.
2. Related Art
In recent years, a technique has been developed, in which white ink is used to form an image on a recording medium (including a light-transmissive recording medium) having a color other than white with the result that a white layer is formed (see, JP-A-2011-020362). In addition, printing is frequently performed onto the container and package of various products, and such printing is called label printing. The label printing is often performed onto a light-transmissive film, and a layer of white ink is preliminarily formed as a base layer on a printing surface in most cases. The formation of the base layer can enhance a property of hiding the back of the film, so that a high-quality image can be formed on the base layer.
Nowadays, an ink jet technique has come to be employed for such image formation. The ink jet technique can reduce the size of equipment as compared with a traditional printing technique and eliminate formation of proofs. The ink jet technique is therefore especially effective to variously perform printing in a small scale and is accordingly promising. In the case of recording information on the container and package of various products, the ink jet technique also generally involves formation of the base layer, and white ink has been developing for the formation of the base layer.
In the case of recording information on light-transmissive media, the base layer formed by using white ink needs to have several properties at least including a property to hide a background, good whiteness, and abrasion resistance. In order to satisfy such properties demanded for the base layer, several techniques have been proposed, in which white ink is applied onto a medium in a larger amount than usual or in which white ink appropriately contains a pigment and fixing resin.
In general, the increase in the amount of the white pigment to be contained in the base layer can enhance the hiding property and whiteness of the base layer, and the increase in the amount of the fixing resin to be contained in the base layer can enhance the abrasion resistance of the base layer. Although adjustment of these properties involves the amount of the white ink to be used (duty) to some extent, it is believed that the white pigment and fixing resin are preferably added to the white ink itself in a large amount in view of, for example, a recording rate.
In an attempt to increase the amount of the white pigment contained in the white ink, unfortunately, precipitation of the white pigment readily occurs. Furthermore, in an attempt to increase the amount of the fixing resin contained in the white ink, ink viscosity increases, and the fixing resin adheres to the white pigment and then becomes solidified (phenomenon called “hard cake”). These problems cause the preservation stability of the white ink to be decreased. Moreover, in the case of ejecting the white ink by an ink jet technique, problems such as clogging may occur. White ink free from these disadvantages is therefore demanded, however, the above requirements are less likely to be sufficiently satisfied only by the change of the composition of the white ink.